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he NACAA convention has been held across Australia since 1967, and has become a significant national forum at which amateur astronomers can exchange experiences, stay abreast of the latest trends, foster co-operative activities between individuals, societies and the professional sphere, and network amongst their peers throughout Australia and beyond.

Programme is ready!

The Programme Committee is pleased to announce that the programme for NACAA XXVI is now ready!!! We have had a huge response from speakers around the country and
internationally. We look forward to an exciting and vibrant event, and wish to thank all those who submitted papers/posters.

Mercury, the closest planet to the Sun, has returned to the evening sky this month for a brief sojourn. Unfortunately you will need a good clear western horizon to see it. By the 19th it should be about 5 degrees above the south-western horizon and only visible for about 30 minutes after the Sun has set. By the end of January it will be visible for closer to 1 hour after Sunset and by mid February it will no longer visible in the evening sky as it heads off to its inferior conjunction appointment with the Sun. It will return later February as the ‘morning star’ and remain in the morning skies until mid April. An inferior conjunction occurs when the Earth and interior planet are on the same side of the Sun.

Venus started the month as the ‘evening star’ after shining so brightly in the western sky on January 11th it Venus passed between the Earth and the Sun and so had its inferior conjunction with the Sun. It will be come visible as the ‘morning star’ before dawn around January 19/20. A nice photo opportunity for all the morning risers will occur on January 29th when a thin crescent Moon will be above Venus to the south-east in the morning twilight.

Earth: trivia note for the month – on January 4, the Earth was at its closest to the Sun for the year. The Sun was only 147,089,638 km away.

Mars is slowly returning to our evening skies in January. Spending the month in the constellation of Virgo it will rise around 12:30am local summer time and rising earlier each night by around 2 minutes, finishing the month by poking its head up around 11:30pm local summer time. Currently the best time to check it out is still in the early morning sky about an hour before morning twilight. On the 23 and 24th of the month the Moon will be very close to Mars at around 12:30am.

Jupiter is visible most of the night at present. It will spend the month in Gemini. It is clearly the brightest object in the sky rising around 8:30pm. By January 22nd it will be setting at around 4:30am. Having reached its yearly opposition – when it’s opposite the sun – rising in the east as the sun is setting in the west on January 5th. Even if you have only a small telescope, or a decent pair of binoculars, which you mount to keep steady the four main moons of Jupiter, Io, Europa, Ganymede and Callisto should be visible. These are the moons that were discovered by Galileo. Although all four may not be visible at the same time as they may be hidden as they pass behind the planets. It is always interesting to watch and note their positions over a few hours – just as Galileo did over 400 years ago.

Saturn rises well before the Sun in the constellation of Libra. By mid January it is rising at around 2am and in the early hours of Australia Day, just before sunrise around 5:30am Venus will be visible very low on the Eastern horizon the Moon and Saturn will be very close and higher in the same line in the sky will be Mars. Between Venus and Saturn is a red star known as Antares – the heart of the Scorpion. Antares also means ‘Mars-Like” so don’t let it trick you! Mars is higher than yellow Saturn in the sky and Antares, a star, is much lower. The rings of Saturn currently are open wide when viewed from the Earth, making them a fine sight in a small telescope.

If you have any questions about what you see in the sky or want more information please feel free to contact me – Donna Burton, University of Southern Queensland – Astronomy for Schools Co-ordinator North West NSW 63 John Street, Coonabarabran 2357, phone 6842 4343 or via email donna.burton@usq.edu.au and you can check out my blog at http://www.astronewsroom.com.

Photo Credits and Caption

Aust_Day_Planets.jpg – Australia Day Morning Planet Parade.

Created in the free planetarium software package – Stellarium. This chart shows you the sky looking East on Australia Day (Jan 26), 2014 at 5:15am AEDST. You will need a good south-eastern horizon but you can see Venus low in the East, the Moon and Saturn and orange-red Mars higher in the sky and to the North.

As usual at this time of the year, the Earth is entering a stream of debris from rock comet 3200 Phaethon, which is the source of the annual Geminid meteor shower. Forecasters expect the shower to peak on Dec. 13-14 with as many as 120 meteors per hour.

This year the nearly full Moon will reduce the number of meteors you may see but it is still well worth a look. Expected to peak from about midnight Friday Australian Eastern Daylight Time (or 1300 UT) until 9pm (1000 UT) Saturday, this meteor shower will be visible in both hemispheres.

Though you do need to keep in mind that meteor showers often peak hours before or after predictions and for sure we certainly don’t know everything that a given meteor stream might have in store!

This shower is an interesting one though, with an equally interesting history and source. The Geminids were first identified as a distinct meteor shower by R.P. Greg of Manchester UK in 1862, and the estimated ZHR rose from about 20 to 80 through the 20th century. The parent source of this shower remained unknown until 1983, when astronomer Fred Whipple linked them to the strange “rock-comet” body 3200 Phaethon. This is an Apollo asteroid also thought to be a member of the Pallas family of asteroids, 3200 Phaethon seems to be shedding enough material to produce the annual Geminid meteor shower. This makes the annual shower rare as one not produced by a comet. It’s worth noting that 3200 Phaethon also passes extremely close – 0.14 AU – from the Sun at perihelion, and gets periodically “baked” during each 1.4 year passage.

In the 21st century, rates for the Geminids have stayed above a Zenith hourly rate (ZHR) of 120, now the highest of any annual shower. It’s worth noting that an extrapolated ZHR of almost 200 were seen in 2011 when the Moon was at an equally unfavorable waning gibbous phase! The Geminids always produce lots of fireballs, capable of being seen even under moonlit skies.

With our warmer nights down under it is a great time to get out and have a look! Jupiter is also looking good after about 10:30pm and Mars and Saturn are visible in the early dawn skies as well.

Tonight we will have a nice dark sky as it is a waning crescent Moon showing only 5% of the visible lunar surface and it will have set by 17:55.

Tonight the Sun will set at 19:53 AEDT and nautical twilight will start at 20:54. This is when the Sun is at an angle of twelve degrees (12°) below an ideal horizon. At this time in the absence of moonlight, artificial lighting or adverse atmospheric conditions, it is dark for normal practical purposes. Astronomical twilight begins at 21:29 and is when the Sun is at an angle of eighteen degrees (18°) below an ideal horizon. At this time the illumination due to scattered light from the Sun is less than that from starlight and other natural light sources in the sky.

Planets visible tonight

Venus: Rises at 7:35 am and sets at 22:07 and is the brightest object in the Western Sky at present.

Jupiter: Rises at 21:42 and sets at 7:44am and is the brightest object in the western morning sky.

Mercury: rises at 3:49am and sets at 17:35pm so is a morning object in the eastern sky.

Mars: rises at 1:13am and sets at 13:04 and is easily visible as a bright orange/red star like object in the early morning sky.

Saturn: rises at 3:31 am and sets at 17:01 and again is only visible in the early morning eastern sky.

The old summer favourites of the Southern Cross and the Large and Small Magellanic Clouds are visible in the South.

The western sky has some of the more fainter constellations visible after sunset as Scorpius and Sagittarius set with Venus. These fainter and less known constellations include Cetus, Eridanus, Phoenix and Sculptor visible.

Looking towards the North and East, you get to see some of the more familiar constellations. During summer the Milky Way runs almost vertically from south to north. Orion has dominates the night sky along with Taurus, Gemini and Cancer.

The comet’s nucleus apparently disrupted near perihelion, with the
comet’s head fading from perhaps a peak brightness of visual mag -2 some hours
before perihelion to well below mag +1 before perihelion. M. Knight, Lowell
Observatory, finds that the comet peaked around visual mag -2.0 around Nov.
28.1 UT, adding that the brightest feature in the coma of the comet faded
steadily after perihelion from about mag 3.1 in a 95″-radius aperture when the
comet first appeared from behind the SOHO coronagraph occulting disk on Nov.
28.92 to about mag 6.5 on Nov. 29.98. K. Battams, Naval Research Laboratory,
writes that, based on the most recent LASCO C3 images (Nov. 30.912 UT), there
is no visible nucleus or central condensation; what remains is very diffuse,
largely transparent to background stars, and fading; it appears that basically
a cloud of dust remains from the nucleus. S. Nakano, Sumoto, Japan, writes
that he measured the comet’s total magnitude in a 27′ photometric aperture
from the SOHO C3 camera images to be as follows: Nov. 29.383, 0.5; 29.755,
1.4; 30.013, 2.0; 30.496, 3.0; 30.883, 5.4.

Z. Sekanina, Jet Propulsion Laboratory, reports that, from the position
of the northeastern boundary of the comet’s fan-shaped tail in three images
taken with the C3 coronagraph onboard the SOHO spacecraft between 0.7 and 1.9
days after perihelion (Nov. 29.46 to 30.66 UT), he finds that the comet’s
production of dust terminated about 3 hours before perihelion. Although this
result is preliminary, it is unlikely to be significantly in error, because
the position angles of a perihelion emission are off in the three images by
14-22 deg, and those of post-perihelion emissions still more. The peak
radiation-pressure accelerations derived from the tail boundary’s angular
lengths (estimated at 1.8-2.5 deg) are about 0.1-0.2 the solar gravitational
acceleration, implying the presence of micron-sized particles. The estimated
time of terminated activity is consistent with the absence of any feature that
could be interpreted as a condensation around an active nucleus in the 20 or
so images taken with the C2 coronagraph on Nov. 28.8-29.0 UT (0.8 to 5.4 hr
after perihelion) and with the appearance of a very sharp tip (replacing a
rounded head) at the comet’s sunward end in the C2 images starting about 4 hr
before perihelion and continuing until its disappearance behind the occulting
disc around Nov. 28.74 UT (or some 50 minutes before perihelion). The time
of terminated activity is here interpreted as the end of nuclear fragmentation,
a process that is likely to have begun shortly before a sudden surge of
brightness that peaked nearly 12 hr prior to perihelion. Fine dust particles
released before perihelion moved in hyperbolic orbits with perihelion
distances greater than is the comet’s, thus helping some of them survive.
The post-perihelion tail’s southern, sunward-pointing boundary consists of
dust ejected during the pre-perihelion brightening. However, the streamer of
massive grains ejected at extremely large heliocentric distances, so
prominently seen trailing the nucleus along the orbit before perihelion (cf.
CBET 3722), completely disappeared. The dust located inside the fan, between
both boundaries, was released in intervening times, mostly during the last
two days before perihelion. The strong forward-scattering effect (phase
angles near 120-130 deg) has tempered the rate of post-perihelion fading of
the comet, but the merciless inverse-square power law of increasing
heliocentric distance is necessarily the dominant factor in the comet’s
forthcoming gradual disappearance.

H. Boehnhardt, J. B. Vincent, C. Chifu, B. Inhester, N. Oklay, B.
Podlipnik, C. Snodgrass, and C. Tubiana, Max Planck Institute for Solar
System Research, Katlenburg-Lindau, reports that two diffuse tail structures
were analyzed in post-perihelion images obtained by the LASCO-C3 corongraph
onboard the SOHO spacecraft between Nov. 29.60 and 29.81 UT. The southward
tail extended toward p.a. about 167 deg to about 0.4 deg distance from the
central brightness peak. The eastward tail had an approximate position angle
of 68 deg and extended to at least 1.2 deg distance. By Finson-Probstein
simulations, the eastward tail can best be interpretated as being caused by a
dust release about 1 hr around perihelion. The maximum beta value in the
eastward tail reaches values up to 1.5, typical for graphite or metallic
grains of about 0.1 micron radius. No indications are found for a
continuation of the release of similar dust after 2 hr post-perihelion. The
shorter southward tail may be a relict of heavier grains released about 1-2
days before perihelion passage. Diffuse cometary material is noticeable in
the p.a. range covered by the two dust tails. The match of the synchrone
pattern for the eastward tail is not optimal, which may indicate secondary
effects to the dust grains involved.

NOTE: These ‘Central Bureau Electronic Telegrams’ are sometimes
superseded by text appearing later in the printed IAU Circulars.

The comet had been visible in the Southern Hemisphere before passing the Sun but since the 19th November it has been very difficult to see as it has risen just before the Sun. After it had passed the Sun it would be rising just after the Sun rise and setting before the Sun set, in the southern hemisphere so hence we would not have been able to see it.

At around 6:44am our time this morning the comet reached perihelion (its closest approach to the Sun) where it broke up and then something continues on – it might just be gravel and dust or there might stay a chunk of rock big enough to stay comet like. But now only time will tell if it is big. This goes to prove that although we certainly know a lot more about comets than we did before – there is a lot more that we do not know. Many have pronounced Comet ISON as already being dead and it certainly will not reach the brightness and spectacular display that had been predicted – but as Mark Twain is often quoted: “Rumours of my demise are greatly exaggerated.” Something emerged from the sun after Comet ISON made its closest approach today. Is it ISON? Both professional and amateur astronomers are analysing images from NASA satellites to learn more about comet’s fate. Northern ground based observers may have to wait until around the 9/10 of December now to see if there is anything to see. But they will not get the amazing views that we were all hoping for.

However, at every single opportunity it could find, Comet ISON has done completely the opposite of what was expected, and it certainly wouldn’t be out of character for this dynamic object to yet again do something remarkable. Even if the comet broke up, it offered a very rare opportunity to see how one of the oldest objects in the solar system interacted with the Sun’s magnetic field and its behaviour in the sun’s magnetic field will help scientists understand more about both comets and the Sun. This was the first comet in recorded history which has come from so far away and passed so close to the sun, passing the sun at a distance of around 1.6 million kms that has been so well-studied and observed.

So we wait and see, this has been one of the most well observed, followed and commented in social media worldwide. A fleet of spacecraft watched ISON plunge toward the sun, including NASA’s STEREO satellite, the European Space Agency/NASA SOHO spacecraft and the Solar Dynamics Observatory. The Hubble Space Telescope should be able to take a close look in a couple of weeks if it did indeed survive.

The photograph above is from the NASA SOHO Space Telescope’s LASCO C3 camera showing a fragment emerging from the other side of the Sun about 3 hours after perihelion.

The picture below is taken this at 00:42UT 1 December 2013 and shows the remnants of the comet as it leaves the SOHO LASCO C# camera’s field of view.

There has been a lot of interest in the Comet 2012/S1 (ISON), more commonly known as Comet ISON. This comet has been predicted to become the comet of the century; this of course, may not eventuate. For those of us fortunate to have witnessed C/2006 P1 (McNaught) in January 2007 it will sure take a lot of beating.

The comet was discovered on 24 September, 2012, by two amateur astronomers in Belarus and Russia, using a 40-cm (16-inch) telescope. As it took them a day to confirm that the object was a comet, the organisation International Scientific Optical Network with which they are associated was credited with the discovery.

Over the past decade, hundreds of sungrazing comets have been discovered, but they are usually small, short-lived, and only seen by spacecraft designed to observe the Sun. Most sungrazing comets do not survive their trip around the Sun as they are disrupted by its intense radiation and gravity. Most of these, however, are quite small being only tens of metres across. The nucleus of Comet Ison is believed to be around 4km in diameter and hopefully its larger size will insulate the interior from the Sun’s energy.

One reason this is considered to be such an interesting comet is that it is believed to be making its first approach to the inner solar system. Along with this belief, comes the reason for all the uncertainty in the predictions as scientists can only guess at how bright it will become at the time it is closest to the Sun. There will be professional and amateur astronomers eagerly observing the comet from the ground and via the internet as a whole fleet of spacecraft have turned their cameras in its direction.

The comet has been gradually brightening as it speeds up on its journey towards the Sun. Unfortunately for us in the Southern Hemisphere just before and just after it passes behind the Sun on November 29, it will be below the horizon in both the morning and evening sky. This is the time that the comet is most likely to be at it brightest. For northern hemisphere observers, at these times, it may even be naked eye or perhaps visible in binoculars. A few weeks later the comet’s outward trajectory, providing it survives its passage around the Sun, will bring it to just 0.4 times the distance from the Earth to the Sun.

But perhaps, the greatest unknown is, in fact whether or not the comet will actually survive its passage through the corona which is the Sun’s atmosphere. At the time it passes the Sun it will only 1.1 million kms away and the nucleus of the comet will be subject to a combination of both extreme heating approximately 5000 degrees Celsius, which is hot enough to melt iron as well as constant radiation bombardment. Add to that the fact that the Sun’s strong gravitational pull will be trying to tear it apart. Still the best guess from scientists is that the nucleus or at least a large chunk of it will manage to sweep around the Sun and start making its way out of the solar system.

Comets are believed to be the frozen left-overs from the formation of our Solar System, originating in the Oort cloud. While comets have been in a deep freeze for the past 4 billion years, planets and asteroids have changed a lot from their original compositions. Better understanding of their ices, dust, and organic matter, and how they have changed over the past billions of years, tell us about the origins of our Sun, the planets, and, possibly, life on Earth. To astronomers, every bright comet is an opportunity to learn more about our Solar System.

NOTE that it is always dangerous to look directly at the Sun. Do not use telescopes or binoculars to search for the comet, just your unaided eyes and block the Sun with a post or other convenient object. Take extreme care!

The position is essential in providing astronomy and/or Australian Aboriginal and cultural astronomy, meteorology and heritage tours night and day which are high quality, with an expert level of knowledge and delivery and a friendly but professional level of customer service to Sydney Observatory visitors.

The tours may be delivered on-site, on another Museum site and through web-based and outreach programs. In providing this the position holder has pre-existing expertise in astronomy and/or the Australian Aboriginal culture and/or cultural astronomy. The position delivers programs as part of a team and may be required to research and advise on delivery.

Applications MUST include cover letter, Resume and a document addressing the SELECTION CRITERIA.

The 26th NACAA will be held over Easter 2014, Friday April 18 to Monday April 21, hosted by the Astronomical Society of Victoria. The NACAA XXVI committees invites everyone interested in the “cutting-edge” of amateur astronomy to attend.

We are working to ensure that the programme will include an exciting mix of invited speakers, technical sessions, group discussions, hands-on workshops, and social functions. The 2014 Berenice Page medal is expected to be presented at the convention dinner. The Sunday night BBQ will be held at the Melbourne Observatory complex in the Botanical Gardens.

The venue for NACAA XXVI is the Rydges Bell City, 215 Bell Street, Preston. Situated in northern Melbourne, Preston is about fifteen minutes by car from Melbourne Airport. It is easily accessed by road via the Hume Freeway, Metropolitan Ring Road and other motorways, and by regular rail services to Bell. As well, the #86 tram travels from central Melbourne (Bourke Street) to the corner of Bell Street and Plenty Road in around 35 minutes.

Registrations for NACAA XXVI will commence in late 2013. A number of registration packages will be available, ranging from attendance at just one or two sessions or workshops, through to a full convention, dinner and BBQ package.

PROGRAMME

The core of the convention is of course its presentations, and we are asking you to consider making a contribution, by yourself or in a group. There are no restrictions on topics or themes, so long as the contribution is significant and interesting. Here are a few suggestions:

An address or poster

on an observational (or desk-bound) research programme you are involved in;

on a significant development in instrumentation and tools: optical, imaging, computational, electronic, whatever …

on your progress with a significant project or programme, national or worldwide;

to share your imaging successes with an appreciative audience;

an entertaining address aimed at promoting the enjoyment of astronomy;

on a significant club or local activity;

on an interesting piece of astronomical history.

A workshop or round-table meeting

on an observing or research technique you use;

helping amateurs move to a more advanced plane of astronomical activity;